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Ajaykumar Rathod1*, Akhil Hadiya2
and Shruti Barmeda1
1Department of Chemistry, KSKV Kachchh University, Bhuj, Gujarat, India.
2Department of Chemistry, Saurashtra University, Rajkot, Gujarat, India.
Corresponding author:ajayrathod.chem@gmail.com
Article Publishing History
Article Received on : 25 Mar 2025
Article Accepted on :
Article Published : 04 Jul 2025
The potential of pyridine, triazole and pyrazoline scaffolds as anticancer, anticonvulsant, antidiabetic, antioxidant, analgesic, antibacterial, neuroprotective, etc. makes them essential intermediates for new drug discovery. Framing pyrazoline scaffolds with triazole and pyridine is a novel approach to design effective drugs. We have prepared a series of pyrazoline incorporated pyridine-triazole ( 6a-o) from Isoiniazid. FT-IR, 1H NMR, 13C NMR, and LCMS spectra were used to describe all produced compounds. The antibacterial and radial scavenging screening were carried out through disc diffusion and DPPH, respectively.
KEYWORDS:Antibacterial; Antifungal; Antioxidant; Pyridine; Pyrazoline; Triazole
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Copy the following to cite this article:Rathod A, Hadiya A, Barmeda S. Synthesis and Biological activities of New Pyrazoline Incorporated Pyridine-Triazole Derivatives. Orient J Chem 2025;41(4).
Rathod A, Hadiya A, Barmeda S. Synthesis and Biological activities of New Pyrazoline Incorporated Pyridine-Triazole Derivatives. Orient J Chem 2025;41(4). Available from: https://bit.ly/4eEoOsl
Introduction
The emergence of bacterial resistance to conventional antibiotics has grown to be a worldwide issue, necessitating the continuous seeking out novel antimicrobial agents. In this regard, heterocycle’s diverse biological activities and structural versatility have drawn significant interest.1–3 Among various heterocyclic scaffolds, pyridine, 1,2,4-triazole, and 4,5-dihydro-pyrazole have demonstrated remarkable potential in medicinal chemistry,4,5 particularly in the development of antimicrobial agents.6
Pyridine is a fundamental nitrogen-containing heterocycle widely found in bioactive molecules. Its unique electronic properties and ability to participate in hydrogen bonding make it a crucial pharmacophore in drug design. Pyridine derivatives possess antibacterial activity,7–9 making them promising candidates for the development of new antimicrobial agents.
Similarly, 1,2,4-triazole is an important five-membered heterocyclic ring known for its therapeutic potential.10–12 The presence of nitrogen atoms in the triazole ring enhances its binding interactions with biological targets, improving its pharmacokinetic and pharmacodynamic properties.13–15 Triazole derivatives have been extensively studied for their role in inhibiting bacterial growth and overcoming resistance mechanisms.
Furthermore, the 4,5-dihydro-pyrazole moiety has been widely explored in medicinal chemistry due to its significant biological activities. Dihydro-pyrazole derivatives are known for their antimicrobial, anti-inflammatory, and anticancer properties.16–18 Their ability to interact with bacterial enzymes and disrupt essential metabolic pathways makes them promising leads in the development of antibacterial agents.
Currently, our team have designed and prepared novel compounds incorporating pyridine, 1,2,4-triazole, and 4,5-dihydro-pyrazole scaffolds to evaluate their antibacterial potential. The efficacy of the newly developed derivatives was assessed by antimicrobial screening. Our findings contribute to the ongoing efforts in developing new antimicrobial agents to combat resistant bacterial strains.
Materials and Methods
Sigma Aldrich is the source of all Initial materials. The Perkin-Elmer RX1 spectrophotometer was used to record the infrared spectra. Using a Brucker 500 MHz spectrometer, the 1HNMR and 13CNMR spectra were captured in CDCl3 solutions. The ElementarVario EL III elemental analyzer was used to perform the elemental analysis. Progress of reaction was recorded by TLC.
General procedure
Synthesis of 1,2,4-triazol-3-thiol derivative(3)
1,2,4-triazol-3-thiol was prepared as per reported method.19 Isoniazid (20 mmol) and ethyl isothiocyanate (20 mmol) in methanol were reflux for 2 hours. The resultant reaction mixture was poured into cold water to isolate compound 2. Compound 2 was solubilized in 20% NaOH and cyclized through reflux for 3 hours. The reaction mixture was acidified by dil HCl to yield 4-ethyl-5-(pyridin-4-yl)-4H-1,2,4-triazole-3-thiol (3). Solids were filtered, dried and recrystallized using ethanol. Yield – 72%
Synthesis of Chalcones derivatives( 4a-o)
Pyrazolines were prepared as per reported method.20,21 acetophenone (50 mmol), various aldehydes (50 mmol), and NaOH (50 mmol) were triturated in a mortar at 300C for 30 minutes. The solid was rinsed with water to remove excess NaOH. The resultant chalcones (4a-4o) were filtered and recrystallized using ethanol. Yield between 80% – 86%
Synthesis of chloro acetyl pyrazoline derivatives( 5a-o)
Compounds (4a-4o) (15 mmol) and hydrazine hydrate (20 mmol) were solubilized in ethanol in FBF. The reaction mixture was subjected to reflux for 11 hours. The solvent was eliminated via distillation to obtain pyrazole. Pyrazoles were subsequently dissolved in dichloromethane. 15 millimoles of chloroacetyl chloride were introduced at 5°C and agitated for seven to eight hours at ambient temperature. Compounds (5a-5o) were obtained via distillation and recrystallized using ethanol.
Synthesis of pyrazoline incorporated pyridine-triazole (6a-o)
4-ethyl-5-(4-pyridinyl)-4H-1,2,4-triazole-3-thiol (0.005 mol) 2-chloro-(5-aryl-3-arylpyrazol-1-yl)ethane-one (0.005 mol) and anhydrous K2CO3 were dissolved in 100 ml DMF. Reaction mass was stirred for 8-9 hours at ambient temperature. The resultant content was then added in the cold water. Solids were filtered off as well as recrystallized with ethyl alcohol. Yield between 62%-71%
Scheme 1: Preparation route of derivatives 6a-o.Click here to View Scheme
Results and Discussion
Biological Screening
Compounds 6a–6o have been screened against S. aureus, B. subtilis, E. coli, E.aerogenes , C.albicans and A.niger using disc diffusion method (figure 1).22 All new compound exhibit moderate to good potential towards bacterial and fungal strains(table 1). When compared to conventional antibiotics, several of these substances exhibit superior inhibitory zones, including compound 6l is quite efficient against B. subtilis and E. coli and it has the maximum activity against S. aureus (36 mm).
Another potent chemical is compound 6e, which exhibits excellent suppression against a variety of pathogens, including a 32 mm zone for S. aureus. Compound 6h has displayed antifungal potential with 22 and 20 mm inhibition against C.albicans and A.niger respectively.
The type of substitution at positions R and R′ markedly changed the studied compounds’ antimicrobial properties. Substitution at R′ with electron-withdrawing groups like 4-nitro (6e) was greatly increased activity, particularly against S. aureus and E. coli, as compared to the unsubstituted comp. 6a. While to a lesser degree, activity was also enhanced by electron-donating groups such as 4-methoxy (6d). In general, adding a methyl group at R (6f–6j) increased potency overall, especially when paired with substituents like 3-nitro or 4-chloro at R′, as compounds 6g and 6j demonstrated, which showed broad-spectrum action. Strong antibacterial effects were produced by methyl substitution at R (6k–6l), with 6l (R = 4-OCH₃, R′ = 4-NO₂) showing the greatest activity among all tested bacteria and even coming close to conventional medicines like amoxicillin. Likewise, chloro substitution at R (6m–6o) in conjunction with groups like 3,4-dimethoxy or 4-dimethylamino improved the antifungal and antibacterial properties even further. The antimicrobial profile was often enhanced by the combination of electron-donating and withdrawing groups, with compounds such as 6j, 6l, and 6o exhibiting particularly strong and wide-ranging action.
Table 1: Antimicrobial activity of 6a-6o
Compound Inhibition Zone (millimeters) S.aureus B.subtilis E.coli E.aerogenes C.albicans A.niger 6a 22 19 17 15 18 17 6b 21 16 13 16 15 15 6c 20 18 12 16 17 15 6d 26 21 16 17 18 18 6e 32 21 18 19 19 18 6f 24 19 13 16 15 14 6g 27 20 19 14 14 15 6h 26 19 18 19 22 20 6i 27 20 17 17 20 19 6j 30 21 18 18 21 19 6k 28 19 18 19 21 20 6l 36 20 21 20 19 18 6m 25 17 19 17 18 20 6n 28 18 18 18 21 21 6o 28 19 17 19 23 22 Amoxicillin 40 28 22 24 – – Ciprofloxacin 40 36 28 30 – – Fluconazole – – – – 28 26
Figure 1: Antimicrobial activity of 6a-6oClick here to View Figure
Antioxidant activities
Radical scavenging activities of compound 6a-6o have been performed at 50,100, 150 µg/ml concentration using ascorbic acid by DPPH method.23 Compound 6l bearing methoxy and nitro substitution has shown highest inhibition with 53 % at 150 µg/ml. while comp 6k with methoxy substitution has shown inhibition with 52.46 % at 150 µg/ml. all other compound have displayed moderate radical scavenging activities.
Table 2: Antioxidant activities
Conc.(µg/ml) Comp. 6a 6b 6c 6d 6e 6f 6g 6h 6i 6j 6k 6l 6m 6n 6o Ascorbic acid 50 22.5 20.4 21.5 24.5 26.7 24.3 23.5 29.6 24.3 24.7 25.4 25.4 24.6 28.7 26.8 83.4 100 34.6 30.4 34.5 35.6 37.7 30.7 32.1 36.6 37.5 37.7 40.2 40.1 34.9 40.4 38.8 87.28 150 39.7 41.3 44 47.1 50.6 38.8 40.2 49.9 51.3 50.2 52.5 53 45.2 50.5 49.5 88.6Chemistry
The synthesis route of pyrazoline incorporated pyridine-triazole molecules is shown in Scheme 1. Pyrazolines (5a-o) were obtained through claisen condensation reaction followed by condensation with hydrazine hydrated and chloroacetyl chloride. Pyridyl-1,2,4-triazole (3) was synthesized through the coupling of isoniazide (1) with ethyl isothyocynate followed by cyclization in the presence of NaOH. 1-(3,5-diphenyl-4,5-dihydro-1H-pyrazol-1-yl)-2-((4-ethyl-5-(pyridin-4-yl)-4H-1,2,4-triazol-3-yl)thio)ethan-1-one (6a-o) derivatives were synthesized by coupling of pyrazoline (5a-o) and Pyridyl-1,2,4-triazole(3) in the presence of anhydrous K2CO3 (Scheme 1).
Spectroscopic methods were used to characterize newly synthesized derivatives (6a-e). Mass spectrum of compound 6a revealed the molecular weight M+H at m/z = 469(Figure 2). The >C=O group’s existence has been shown by the absorption band at 1674 cm⁻¹ in the IR spectra of comp. 6a. The C-H- stretching bands has been located at 3055 and 2974 cm⁻¹. Vibrations at 1427 cm⁻¹, caused by –C-N< stretching, indicated the existence of a pyrazoline ring(Figure 3).
The presence of 14 and 10 protons of compound 6a in the aromatic and aliphatic regions were confirmed by 1H NMR spectra (Figure 4). Three double doublets at 3.1, 3.7, & 5.5 δ ppm in 1H-NMR spectrum indicate an AMX pattern rising due to the vicinal interaction of two diastereomeric and one methine protons of pyrazoline. The existence of an ethyl chain of triazole has been shown by the 1H NMR spectrum, which displays a triplet at 1.3 ppm and a quartet peak at 4.0 δ ppm. A singlet at 8.7 ppm of 1H-NMR spectrum indicates the existence of pyridine ring.
The 13CNMR spectra displayed a distinctive peak at δ=164 ppm, which resulted from carbonyl group. The ethyl chain has shown peak at δ = 15.62 ppm, whereas the pyrazoline ring showed signals at 60.51 & 42.2 δ ppm (Figure 5).
Figure 2: Mass spectrum of comp. 6aClick here to View Figure
Figure 3: FT-IR of comp. 6a Click here to View Figure
Figure 4: 1H NMR of comp. 6aClick here to View Figure
Figure 5: 13C NMR of comp. 6aClick here to View Figure
Characterization
Compound 6a
Scheme 2Click here to View Scheme
Yellow solid, Molecular Formula: C26H24N6OS; FT-IR (cm-1, KBr): 3028, 2935, 2974.33, (C-H), 1674 (C=O), 1600 (C=C -Ar), 1427 (C=N – triazole), 702 (str of S-C); 1H NMR: 1.33 (H, CH3), 3.20, 3.81 (dd, H, Pyrazoline), 4.05, 4.75 (2H,CH2), 5.58 (dd,H,CH), 7.23-8.76 (14H, Ar-H) ; 13C NMR (500 MHz, δ ppm CDCl3): 15.61, 37.31, 40.16, 42.44, 60.60, 122.28, 125.72, 126.89, 127.89, 128.82, 128.99, 130.80, 130.82, 135.04, 141.05, 150.56, 152.14, 153.03, 155.42 164.86; Mass: M+H 469
Compound 6b
Scheme 3Click here to View Scheme
Yellow solid, Molecular Formula:C26H23ClN6OS; FT-IR (cm-1, KBr): 3042, 2972, 2929 (C-H), 1677 (C=O), 1599 (C=C -Ar), 1431 (C=N – triazole), 710 (S-C); 1H NMR : 1.31 (H, CH3), 3.21, 3.77 (dd, H, Pyrazoline), 4.04, 4.76 (2H,CH2), 5.56 (dd,H,CH), 7.26 – 8.80 (13H, Ar-H); 13C NMR (500 MHz, δ ppm CDCl3): 15.63, 37.35, 40.19, 42.45, 60.39, 122.29, 125.75, 126.88, 127.89, 128.82, 128.91, 129.51, 135.04, 141.15, 141.30, 150.57, 152.16, 153.04, 155.54, 164.78; Mass: M+H 503
Compound 6c
Scheme 4Click here to View Scheme
Yellow solid, Molecular Formula:C27H26N6OS; FT-IR (cm-1, KBr): 3055, 2969, 2926 (C-H) 1671 (C=O), 1602 (C=C -Ar), 1422 (C=N – triazole), 708 (S-C); 1H NMR : 1.32 (H, CH3), 2.43 (H, CH3) 3.24, 3.82 (dd, H, Pyrazoline), 4.05, 4.75 (2H,CH2), 5.54 (dd,H,CH), 7.21 – 8.77 (13H, Ar-H); 13C NMR (500 MHz, δ ppm CDCl3): 15.63, 21.55, 37.37, 40.13, 42.47, 60.49, 122.25, 125.71, 126.84, 127.83, 128.02, 128.95, 129.51, 135.04, 141.14, 141.28, 150.55, 152.16, 153.00, 155.52, 164.74; Mass: M+H 483
Compound 6d
Scheme 5Click here to View Scheme
Yellow solid, Molecular Formula:C27H26N6O2S; FT-IR (cm-1, KBr): 2941, 2968, 3035 (C-H), 1665 (C=O), 1605 (C=C Ar), 1421 (C=N – triazole), 699 (S-C); 1H NMR : 1.33 (H, CH3), 2.89 (H, OCH3) 3.15, 3.78 (dd, H, Pyrazoline), 4.04, 4.79 (2H,CH2), 5.58 (dd, H,CH), 7.24 – 8.82 (13H, Ar-H); 13C NMR (500 MHz, δ ppm CDCl3): 15.63, 37.33, 40.15, 42.39, 55.89, 60.47, 114.66, 122.21, 125.75, 126.87, 128.79, 128.95, 130.81, 135.06, 141.04, 150.54, 152.11, 153.00, 154.21, 155.41, 164.81; Mass: M+H 499
Compound 6e
Scheme 6Click here to View Scheme
Yellow solid, Molecular Formula:C26H23N7O3S; FT-IR (cm-1, KBr): 2942, 2981, 3033 (C-H), 1669 (C=O), 1606 (C=C Ar), 1419 (C=N – triazole), 699 (str of S-C); 1H NMR : 1.33 (H, CH3), 3.11, 3.76 (dd, H, Pyrazoline), 4.06, 4.73 (2H,CH2), 5.56 (dd,H,CH), 7.24 – 8.76 (13H, Ar-H); 13C NMR (500 MHz, δ ppm CDCl3): 15.61, 37.31, 40.16, 42.44, 60.48, 122.22, 125.69, 126.87, 127.87, 128.85, 128.97, 130.82, 135.04, 141.01, 144.23, 150.57, 152.11, 153.01, 155.45, 164.81; Mass: M+H 514
Compound 6f
Scheme 7Click here to View Scheme
White solid, Molecular Formula:C27H26N6OS; FT-IR (cm-1, KBr): 3032, 2978, 2931 (C-H), 1666 (C=O), 1597 (C=C Ar), 1435 (C=N – triazole), 709 (str of S-C); 1H NMR: 1.33 (H, CH3), 2.39 (H, CH3) 3.16, 3.78 (dd, H, Pyrazoline), 4.05, 4.70 (2H,CH2), 5.55 (dd, H,CH), 7.21 – 8.75 (13H, Ar-H); 13C NMR (500 MHz, δ ppm CDCl3): 15.62, 21.54, 37.38, 40.15, 42.48, 60.50, 122.27, 125.72, 126.86, 127.85, 128.05, 128.96, 129.52, 135.03, 141.13, 141.25, 150.56, 152.17, 153.02, 155.51, 164.75; Mass: M+H 483
Compound 6g
Scheme 8Click here to View Scheme
White solid, Molecular Formula:C27H25ClN6OS; FT-IR (cm-1, KBr): 2953, 2977, 3044 (C-H), 1668 (C=O), 1608 (C=C Ar), 1431 (C=N – triazole), 707 (str of S-C); 1H NMR : 1.32 (H, CH3), 2.40 (H, CH3) 3.14, 3.79 (dd, H, Pyrazoline), 4.06, 4.71 (2H,CH2), 5.55 (dd,H,CH), 7.23 – 8.78 (12H, Ar-H); 13C NMR (500 MHz, δ ppm CDCl3): 15.63, 37.32, 40.15, 42.42, 60.56, 122.25, 125.74, 126.84, 127.84, 128.78, 128.93, 135.06, 141.44, 141.43, 150.56, 152.11, 153.08, 155.46 164.70; Mass: M+H 517
Compound 6h
Scheme 9Click here to View Scheme
White solid, Molecular Formula:C29H30N6O3S; FTIR (cm-1, KBr): 2942, 2968, 3024(C-H) 1675 (C=O amide), 1602 (C=C – aromatic), 1421 (C=N str – triazole), 702 (str of S-C); 1.33 (H, CH3), 2.41 (H, CH3) 2.96 (H, OCH3) 3.12, 3.82 (dd, H, Pyrazoline), 4.04, 4.71 (2H,CH2), 5.56 (dd, H,CH), 7.23 – 8.79 (11H, Ar-H); 13C NMR (500 MHz, δ ppm CDCl3): 15.62, 21.59, 37.34, 40.17, 42.46, 55.86, 60.35, 122.28, 125.74, 126.82, 127.88, 128.01, 128.95, 129.49, 135.09, 141.14, 141.38, 150.58, 152.14, 153.04, 155.54, 164.73; Mass: M+H 543
Compound 6i
Scheme 10Click here to View Scheme
Yellow solid, M. Formula :C29H31N7OS; FTIR (cm-1, KBr): 2942, 2981, 3043 (C-H), 1666.70 (C=O amide), 1597.60 (C=C- aromatic ring), 1426 (C=N – triazole), 693 (S-C); 1.32, 2.40 (H, CH3) 2.99 (6H, CH3) 3.14, 3.81 (dd, H, Pyrazoline), 4.06, 4.75 (2H,CH2), 5.59 (dd, H,CH), 7.20 – 8.75 (13H, Ar-H); 13C NMR (500 MHz, δ ppm CDCl3): 15.64, 21.56, 37.39, 40.13, 42.42, 42.55, 60.29, 112.24, 122.27, 125.72, 126.86, 127.85, 128.91, 129.69, 135.09, 141.15, 141.28, 150.53, 152.11, 153.11, 155.58, 164.69; Mass: M+H 526
Compound 6j
Scheme 11Click here to View Scheme
Yellow solid, M Formula :C27H25N7O3S; FTIR (cm-1, KBr): 2935, 2965, 3050, (C-H), 1677.40 (C=O amide), 1610 (C=C -Ar), 1431 (C=N– triazole), 709 (S-C); 1.33 (H, CH3), 2.42 (H, CH3), 3.11, 3.79 (dd, H, Pyrazoline), 4.05, 4.72 (2H,CH2), 5.55 (dd, H,CH), 7.23 – 8.81 (13H, Ar-H); 13C NMR (500 MHz, δ ppm CDCl3): 15.62, 21.55, 37.32, 40.14, 42.41, 60.46, 122.28, 125.76, 126.84, 127.85, 128.06, 128.89, 129.48, 135.01, 141.09, 141.17, 150.53, 152.15, 153.03, 155.50, 164.72; Mass: M+H 528
Compound 6k
Scheme 12Click here to View Scheme
White solid, M. Formula:C27H26N6O2S; FTIR (cm-1, KBr): 2930, 2971, 3022 (C-H), 1667 (C=O amide), 1611 (C=C -aromatic), 1426 (C=N – triazole), 707 (str of S-C); 1H NMR : 1.33 (H, CH3), 2.94 (H, OCH3) 3.11, 3.85 (dd, H, Pyrazoline), 4.04, 4.81 (2H,CH2), 5.54 (dd, H,CH), 7.26 – 8.79 (14H, Ar-H); 13C NMR (500 MHz, δ ppm CDCl3): 15.64, 21.56, 37.30, 40.12, 42.42, 56.12, 59.90, 122.21, 125.68, 126.85, 127.83, 128.01, 128.95, 129.54, 135.01, 141.10, 141.22, 150.52, 152.16, 153.05, 155.56, 164.79; Mass: M+H 499
Compound 6l
Scheme 13Click here to View Scheme
White solid, Molecular Formula:C27H25N7O4S; FTIR (cm-1, KBr): 2946, 2983, 3042 (C-H ), 1665 (C=O amide), 1598 (C=C- aromatic ring), 1419 (C=N– triazole), 698 (str of S-C); 1H NMR : 1.32 (H, CH3), 3.01 (H, OCH3) 3.15, 3.86 (dd, H, Pyrazoline), 4.07, 4.78 (2H,CH2), 5.60 (dd, H,CH), 7.21 – 8.78 (13H, Ar-H); 13C NMR (500 MHz, δ ppm CDCl3): 15.62, 21.56, 37.37, 40.20, 42.49, 55.98, 60.30, 122.21, 125.72, 126.86, 127.81, 128.00, 128.91, 129.46, 135.07, 141.18, 141.34, 150.51, 152.14, 153.08, 155.59, 164.76; Mass: M+H 544
Compound 6m
Scheme 14Click here to View Scheme
White solid, Molecular Formula:C26H23ClN6OS; FTIR (cm-1, KBr): 2928, 2971, 3032, 3059 (C-H), 1677.40 (C=O amide), 1606 (C=C Ar), 1421 (C=N – triazole), 709 (S-C); 1H NMR: 1.32 (H, CH3), 2.45 (H, CH3), 3.11, 3.79 (dd, H, Pyrazoline), 4.07, 4.78 (2H,CH2), 5.55 (dd, H,CH), 7.22 – 8.83 (12H, Ar-H); 13C NMR (500 MHz, δ ppm CDCl3): 15.62, 21.54, 37.38, 40.15, 42.48, 60.50, 122.27, 125.72, 126.86, 127.85, 128.05, 128.96, 129.52, 135.03, 141.13, 141.25, 150.56, 152.17, 153.02, 155.51, 164.75; Mass: M+H 504
Compound 6n
Scheme 15Click here to View Scheme
Pale yellow solid, Molecular Formula:C28H27ClN6O3S; FTIR (cm-1, KBr): 2945, 2984, 3039 (C-H), 1675 (C=O amide), 1612 (C=C- aromatic), 1424 (C=N – triazole), 706 (S-C); 1H NMR: 1.31 (H, CH3), 2.96 (6H, OCH3) 3.12, 3.79 (dd, H, Pyrazoline), 4.05, 4.79 (2H,CH2), 5.56 (dd,H,CH), 7.19 – 8.74 (11H, Ar-H); 13C NMR (500 MHz, δ ppm CDCl3): 15.63, 21.56, 37.38, 40.12, 42.47, 56.81, 60.29, 122.25, 125.75, 126.85, 127.88, 128.04, 128.92, 129.42, 135.03, 141.16, 141.27, 150.56, 152.17, 153.08, 155.56, 164.71; Mass: M+H 564
Compound 6o
Scheme 16Click here to View Scheme
Pale yellow solid, Molecular Formula:C28H28ClN7OS; FTIR (cm-1, KBr): 2940, 2979, 3035, 3061 (C-H), 1678.30 (C=O amide), 1612 (C=C – aromatic ring), 1419 (C=N – triazole), 694 (S-C); 1H NMR: 1.31 (H, CH3), 2.88 (6H, CH3) 3.12, 3.77 (dd, H, Pyrazoline), 4.04, 4.77 (2H,CH2), 5.58 (dd,H,CH), 7.24 – 8.82 (13H, Ar-H); 13C NMR (500 MHz, δ ppm CDCl3): 15.61, 21.53, 37.31, 40.12, 42.43, 42.55, 60.29, 122.25, 125.70, 126.81, 127.85, 128.03, 128.88, 129.47, 135.01, 141.16, 141.24, 150.55, 152.18, 153.05, 155.57, 164.69; Mass: M+H 547
Elemental analysis (EA)
Table 3: Physical data and elemental analysis
Compound R R’ Formula MP0C Yield% EA Proposed % Found% C H N S C H N S 6a H H C26H24N6OS 142 65 66.65 5.16 17.94 6.84 66.6 5.08 17.85 6.75 6b H 4-Cl C26H23ClN6OS 146 71 62.08 4.61 16.71 6.37 62.0 4.50 16.62 6.31 6c H 4-CH3 C27H26N6OS 140 62 67.20 5.43 17.41 6.64 67.2 5.35 17.33 6.54 6d H 4-OCH3 C27H26N6O2S 154 68 65.04 5.26 16.86 6.43 65.0 5.20 16.80 6.30 6e H 4-NO2 C26H23N7O3S 174 65 60.81 4.51 19.09 6.24 60.8 4.41 19.01 6.15 6f 4-CH3 H C27H26N6OS 160 69 67.20 5.43 17.41 6.64 67.2 5.4 17.30 6.59 6g 4-CH3 4-Cl C27H25ClN6OS 158 63 62.72 4.87 16.25 6.20 62.7 4.75 16.17 6.20 6h 4-CH3 3,4-di OCH3 C29H30N6O3S 146 62 64.19 5.57 15.49 5.91 64.1 5.50 15.42 5.80 6i 4-CH3 4-N(CH3)2 C29H31N7OS 136 65 66.26 5.94 18.65 6.10 66.2 5.80 18.59 6.00 6j 4-CH3 3-NO2 C27H25N7O3S 144 68 61.47 4.78 18.58 6.08 61.4 4.71 18.50 6.00 6k 4-OCH3 H C27H26N6O2S 128 71 65.04 5.26 16.86 6.43 65.0 5.18 16.80 6.30 6l 4-OCH3 4-NO2 C27H25N7O4S 158 70 59.66 4.64 18.04 5.90 59.6 4.53 17.92 5.80 6m 4-Cl H C26H23ClN6OS 144 64 62.08 4.61 16.71 6.37 62.0 4.51 16.65 6.25 6n 4-Cl 3,4-di OCH3 C28H27ClN6O3S 134 69 59.73 4.83 14.93 5.69 59.7 4.75 14.82 5.60 6o 4-Cl 4-N(CH3)2 C28H28ClN7OS 130 66 61.58 5.17 17.95 5.87 61.5 5.05 17.90 5.81Conclusion
Potent triazole-pyridine fused pyrazoline derivatives 6a-6o were synthesized from pyrazoline and 3-mercapto triazole. Potential as antimicrobial agents was demonstrated by screening against bacterial and fungal strains. Methoxy and nitro functionalized com. 6l has shown highest inhibition towards S. aureus, E. coli, E.aerogenes. All compounds have demonstrated modest scavenging capabilities where methoxy substitution promotes antioxidant activities.
Acknowledgment
We acknowledge the laboratory resources provided by K.S.K.V. Kachchh University, Bhuj.
Funding Sources
The author(s) received no financial support for the research, authorship, and/or publication of this article.
Conflict of Interest
The author(s) do not have any conflict of interest.
Data Availability Statement
This statement does not apply to this article.
Ethics Statement
This research did not involve human participants, animal subjects, or any material that requires ethical approval.
Informed Consent Statement
This study did not involve human participants, and therefore, informed consent was not required.
References
Kabir, E.; Uzzaman, M. A ; Results Chem.2022, 4, 100606.
This work is licensed under a Creative Commons Attribution 4.0 International License.
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